My radiator fan does not kick on now until the gauge gets to half way line and it comes on slow. I have changed the high speed relay and the cooling temp sensor. Now if you run a wire to it straight to the battery it will run on high speed. Is there another sensor that controls the speed of the fan? What else can make the fan only run on slow and not high?

 

I have not found a wiring diagram / schematic for late model Sonics . If anyone can post one , I would be happy to help you read it .

It should be driven by relay , which you have changed . Relay in turn driven by the computer .

When you ran 12 VDC to the fan , does the fan wiring have a high speed and a low speed wire ?

Does the engine overheat ?

I can not remember our 2015 Sonic having any kind of temperature display on the dash ?

I have ordered this OBDII Bluetooth adapter . And software for my Android phone . Has not arrived from China , yet .

Mini ELM327 Bluetooth Auto OBDII Car Scanner for Android Torque Elm 327 OBD 2 | eBay

Something like that might give you more information .

Also , use something like this to measure the temperature of the coolant leaving the engine , going to the radiator .

Non-Contact Infrared Thermometer With Laser Targeting

God bless
Wyr

 

NO THE ENGINE DOES NOT OVERHEAT AT ALL. i HAVE THE WIRE GOING STRAIGHT TO BATTERY. tHE FAN HAS ALL WAYS WORKED FINE UP TILL RECENTLY.

 

are you sure the fan should be running? unless you have a/c or defrost on the fan normally doesn't operate until a set temp. and its usually higher than the midway point

 

Have a 2009 Aveo, about 95K miles and I cannot recall ever seeing the fan running. Often I think that it must be defective.

 

Well it does come on otherwise the temp will go up pass halfway which is not good. I never paid it no attention before until really now. I see it kicks on when temp gets to halfway but it comes on slow but it never kicks into high speed. HMMM? Weird.

 

If the fan runs 100% speed , with a wire directly to the battery & not when connected to the factory wiring harness ? I would suspect the factory wiring harness .

Can you post photos of the place where the relay is located & plugged in ?

On older GM cars , I have seen the same relay used on several different places / spots / circuits . If you have that situation , an easy trouble shooting tip is to swap the identical relays into different sockets / position . And see if this changes anything .

I think you said you installed a new relay ? Is it possible you replaced the wrong one ?

If this does not help , Check the ground wire / connection to the fan . Also , with an ohm meter , you can check the wiring from the pin of the relay socket that feeds the fan , to the connector of the factory fan wiring harness . To see if there is a questionable wire in that wiring harness .

God bless
Wyr

 

Ok thanks will have it checked out and see. I am not close by the car at this time for a picture.

 

So , what is the outcome ?

God bless
Wyr

 

2009 Aveo 1.6L (newer style engine), 98K miles, replaced: timing belt, water pump, radiator hoses, heater inlet hose, thermostat, drivers side doors, ++++

Fan turned on last night, needle was 3/4 from the bottom, once on the engine temp dropped to the center line very quickly.

It was on high speed, yesterday was the first warm day in months.

Running dex cool 50/50 tank is filled as it should be.